1. Field of the Invention
The present invention relates to a data filing system, and more particularly to a system for storing, retrieving and reproducing image data.
2. Description of the Background Art
In the case of photographs for use in engineering, such as images of a waveform displayed on the screen of an oscilloscope, an area of interest to be observed by an engineer is not always the whole area but often part of the screen. This is also the case with images recorded by measuring instruments, such as a spectrum analyzer, and further with an image data file in which images are recorded and analyzed in the form of digital data. Specifically, even when it is sufficient that only a part of interest of an image is reproduced, the entire area of the image frame is read out from the image data file. Also in the case of a composite picture or montage photograph, a photographic certificate or the like, what is actually required may frequently be only a portion of the area of an image frame, for example, a face portion of a person. Even in such a case, the data of the entire area of the image is read out and then an area of interest of the entire image is enlarged and taken out from the data.
Image data itself in principle has a high level of redundancy. Consequently, an image data file in which images are recorded on a digital data basis is large in size , since it involves a large amount of data. Thus, according to a system which requires the whole picture area of an image to be read out even where it is sufficient to retrieve data of only a portion of interest of the recorded image, it takes a lot of time for reproducing and retrieval. Specifically, a memory device which is slow in retrieval and transfer rate takes a remarkably long time for retrieval. With respect to the compsite photograph and the photographic certificate, there is adopted, to take out a part of interest of an image, a system which performs clipping such that data of the entire area of an image is read out and then a portion of interest of the image, such as of the face portion of a person, is enlarged. Thus, this also involves such a drawback that it takes a lot of time for retrieval.
Further, hitherto, in the case where still images such as still pictures or photographs are managed, for example, at home or the like, photographs each having a predetermined size are stored in a book-style album in such a manner that a plurality of pictures are sequentially pasted on pages of the album. In this case, it is possible to watch a plurality of images and also to easily locate a desired image by turning over sequentially the pages of the album. Further, it is possible to sort the related images on an album-by-album basis and also to easily locate an album including a desired image with associated indexes appended to the respective albums. However, the increased number of pictures involves an increased number of album volumes. Specifically, the increased number of album volumes, such as 10, 20 volumes, will cause such problems that a large space for storage is needed and the management is not easy. Further, safekeeping of those albums for years will bring about discoloration of the pictures, and will involve such a problem that pictures may inadvertently be broken when the pictures are repasted for rearrangement.
In view of the foregoing, recently, there has been developed an image recording system in which a still image such as a still picture is read by an image reader such as an image scanner and is converted into digital data, the data are each generated in the form of a data file which is able to be displayed on a display unit, and the data files are recorded on a large capacity optical disc such as a compact disc (CD). In this case, for example, an image file of the image data thus read is recorded on an optical recording medium together with data of key words, such as a file name, a photographer, a photographing date and the title of the image. Thus, when reproducing a desired image, entry of the key words such as a file name, a title or the like permits the image file of interest to be retrieved. When the entered key words, such as a photographer and a photographic date, are directed to a plurality of image files, these key words are first entered to retrieve an associated plurality of image files, and then an additional key word different from the earlier entered key word is entered to narrow the objects to be hit. This work is repeatedly carried out to locate the image of interest.
Further, for example, in Japanese Patent Laid-Open Publication No. 181905/1993, there is proposed a retrieval information display system in which pictures photographed by a digital still camera or the like are recorded in a memory card, from which a desired photographic picture is retrieved. That system is provided with a multi-screen, which includes a plurality of sections of a full screen corresponding to a plurality of pictures, to display a plurality of small pictures on the respective screen sections, on one of which displayed is single, representative one of the small pictures corresponding to the pictures consecutively captured, or related to each other, thereby facilitating retrieval.
The conventional system as described above, however, suffers from the following drawbacks.
Storage of a number of picture files, for example, near 1000 sheets, in a sheet of optical disc will make it difficult to readily manage the picture files as in the case of photographic albums. Specifically, where a desired picture is retrieved through key words and the like, for example, if a single key word is involved in a number of picture files, it is necessary for an operator to remember a number of key words mutually different and input them a number of times until a desired picture file is reached. In this case, if the operator forgets any of the key words, it would be impossible to perform the retrieval. On the other hand, it could be considered that a desired picture file is retrieved by such small screen sections only. In this case, however, it would cost much time and labor to locate a desired picture through scrolling the screen sections for several hundered sheets of the picture file.
Further, in the case of generating small pictures, the small pictures are formed with a desired size by thinning inputted pictures. However, if the size of the inputted pictures is not uniform, the size of the generated small pictures will not be unified. This involves such a problem that when those generated small pictures are displayed altogether on a display unit there occurs a difficulty in arranging them on the area of the picture screen. Furthermore, when a file for storing small picture data is formed, even though the respective storage capacities allotted to sheets of small picture data are small, a file for storing, for example, 1000 sheets of small picture data will require several tens of megabytes in capacity. This may cause difficulties such as frequent failures in recording to a recording medium, thereby giving rise to a difficulty in handling the files.